U.S. patent number 5,352,971 [Application Number 08/029,564] was granted by the patent office on 1994-10-04 for electronic control apparatus for a vehicle.
This patent grant is currently assigned to Mitsubishi Denki Kabushiki Kaisha. Invention is credited to Yukinobu Nishimura.
United States Patent |
5,352,971 |
Nishimura |
October 4, 1994 |
Electronic control apparatus for a vehicle
Abstract
An output current of an alternator and a load current are
detected by current sensors 5 and 6. When the output current of the
alternator has a predetermined value or lower, generation of
electricity by the alternator is stopped. When the load current has
a predetermined value or higher, generation of electricity is
resumed. When the load current is increased, a load-responsive
control for the alternator and an intake air increasing control is
performed, and the generation of electricity of the alternator is
stopped at an acceleration time of the engine, and the output of
the alternator is gradually increased.
Inventors: |
Nishimura; Yukinobu (Himeji,
JP) |
Assignee: |
Mitsubishi Denki Kabushiki
Kaisha (Tokyo, JP)
|
Family
ID: |
14012573 |
Appl.
No.: |
08/029,564 |
Filed: |
March 11, 1993 |
Foreign Application Priority Data
|
|
|
|
|
Apr 10, 1992 [JP] |
|
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4-090944 |
|
Current U.S.
Class: |
322/27; 322/25;
322/28 |
Current CPC
Class: |
H02J
7/1446 (20130101); Y02T 10/92 (20130101) |
Current International
Class: |
H02J
7/14 (20060101); H02J 007/14 () |
Field of
Search: |
;322/25,27,28
;123/339 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Hickey; R. J.
Attorney, Agent or Firm: Sughrue, Mion, Zinn, Macpeak &
Seas
Claims
What is claimed is:
1. An electronic control apparatus for a vehicle, comprising:
an alternator for charging a battery and supplying a load
current,
means for detecting an output current from the alternator,
means for detecting the load current,
means for comparing the detected output current to a first
predetermined value and comparing the detected load current to a
second predetermined value, and
means for stopping, for a predetermined time, generation of
electricity by the alternator when the comparing means determines
that the output current is one of less than and equal to the first
predetermined value and for allowing the alternator to resume
generating electricity when the comparing means determines that the
load current is one of greater than and equal to the second
predetermined value.
2. An electronic control apparatus for a vehicle having an engine,
comprising:
an alternator for charging a battery and supplying a load
current,
a detector for detecting the load current,
means for determining, in accordance with the detected load
current, whether the load current is increasing, and
means for controlling the alternator to stop generating electricity
for a predetermined time when the determining means determines that
the load current is increasing, and after the predetermined period
of time has elapsed, controlling the alternator to gradually
increasingly generate electricity and controlling an engine air
input to gradually increasingly supply air to the engine.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electronic control apparatus
for a vehicle for performing control an alternator in association
with controlling the number of revolutions of the engine during
idling.
2. Discussion of Background
There has been known a method of controlling generation of
electricity in an alternator, as shown in, for instance, Japanese
Unexamined Patent Publication No. 222099/1984, in which a load
current is detected and an electrical voltage is changed depending
on the value of detected load current.
Further, in a method of controlling the number of revolutions
during idling in association with control of an alternator, there
has been known, for instance, Japanese Unexamined Patent
Publication No. 170553/1988 in which air quantity is controlled. In
the publication, a current through an electrical load is detected
and the number of revolutions of the engine during idling is
controlled depending on the detected load current.
A technique of controlling an alternator is disclosed in, for
instance, Japanese Unexamined Patent Publication No. 248238/1986.
In this technique, an output current from an alternator is
determined from an intermittent signal produced by feeding and
interrupting a current to the field coil of the alternator, i.e. a
field duty signal, and the current to be supplied to the field coil
is forcibly turned off in an increase of the duty, and thereafter,
the current is turned on to perform control for gradually
increasing the duty.
The conventional control of generation of electricity in the
alternator is conducted based on either a load current or a battery
charging current, and accordingly, when the generation of
electricity is stopped when a small load current is being provided,
the charging to the battery is insufficient. On the other hand,
when the generation of electricity is stopped when a large charging
current is being provided to the battery, a danger of exhaustion of
the battery exists. Further, when the generation of electricity is
stopped when small charging current is being provided to the
battery, there is a problem that the battery may be exhausted when
a large electrical load is applied.
In controlling the number of revolutions of the engine during
idling in association with controlling an alternator, there are two
techniques: a technique of controlling an air quantity in response
to an electrical load current and a load-responsive control
technique wherein the output of the alternator is stopped by
controlling the same when the output of the alternator is
increased, and thereafter, the output is gradually increased.
In the former case, it is impossible to prevent a drop of
revolution number at the initial stage of the connection of an
electrical load since the air quantity is controlled. On the other
hand, in the later case, it is also impossible to prevent a drop in
the number of revolutions of the engine at the time of the
connection of an electrical load since determination is made upon
an increase in the field duty.
In a case that the output of the alternator is forecast from a
field duty, an output current is obtained from the calculation of a
field duty multiplied with a revolution number of engine when a
load to the engine is light. However, in this technique, there is a
large error because a resistance in the field coil is changed by an
ambient temperature, whereby the performance of control is
poor.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an electronic
control apparatus for a vehicle which is capable of reducing fuel
cost, improving the output performance as well as idle quality with
a simple structure by controlling the alternator in association
with controlling idling resolution.
In accordance with the present invention, there is provided an
electronic control apparatus for a vehicle which comprises an
alternator for charging a battery and supplying a load current,
means for directly or indirectly detecting an output current from
the alternator, means for directly or indirectly detecting the load
current, and means for stopping, for a predetermined time,
generation of electricity in the alternator when the output current
has a predetermined value or lower and containing the generation of
electricity when the load current has a predetermined value or
higher.
Also in accordance with the present invention, there is provided an
electronic control apparatus for a vehicle which comprises an
alternator for charging a battery and supplying a load current,
means for directly or indirectly detecting the load current, and
means for stopping for a predetermined time generation of
electricity in the alternator when the load current is increased,
and, thereafter, gradually increasing the output of the alternator
as well as increasing an air quantity to be supplied to the
engine.
Further in accordance with the present invention, there is provided
an electronic control apparatus for a vehicle which comprises an
alternator for charging a battery and supplying a load current,
means for detecting an acceleration of the engine, and means for
stopping, for a predetermined time, generation of electricity in
the alternator when the engine is accelerated, and, thereafter,
gradually increasing the output of the alternator.
BRIEF DESCRIPTION OF DRAWINGS
A more complete appreciation of the invention and many of the
attendant advantages thereof will be readily obtained as the same
becomes better understood by reference to the following detailed
description when considered in connection with the accompanying
drawings, wherein:
FIG. 1 is a block diagram of an embodiment of the electronic
control apparatus according to the present invention;
FIG. 2 is a flowchart showing the operation of controlling
generation of electricity at an acceleration time in the electronic
control apparatus shown in FIG. 1;
FIGS. 3(a)-3(g) comprise a time chart showing the operation of
controlling generation of electricity at an acceleration time in
the electronic control apparatus according to the present
invention;
FIG. 4 is a flowchart showing the operation of controlling
generation of electricity when a light load is applied in the
electronic control apparatus of the present invention;
FIGS. 5(a)-5(e) comprise a time chart showing the operation of
controlling generation of electricity when a light load is applied
in the electronic control apparatus;
FIG. 6 is a flowchart showing the operation of a load-responsive
control in the electronic control apparatus of the present
invention;
FIGS. 7(a)-7(f) comprise a time chart showing the operation of a
load-responsive control in the electronic control apparatus;
FIGS. 8(a)-8(b) comprise a time chart showing a load correcting
operation in an idling revolution control for the electronic
control apparatus of the present invention;
FIG. 9 is a diagram of a second embodiment of the electronic
control apparatus according to the present invention; and
FIG. 10 is a diagram showing a current sensor used for the second
embodiment of the electronic control apparatus of the present
invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to the drawings, the electronic control apparatus of the
present invention will be described.
FIG. 1 is a block diagram showing the construction of a first
embodiment of the electronic control apparatus or a vehicle wherein
reference numeral 1 designates a battery, and numeral 2a designates
a battery voltage signal. Numeral 2 designates an alternator which
controls, as the basic function, an output current 2b based on the
battery voltage signal 2a and a voltage signal produced by itself,
and controls, as another function, the output current 2b by a
controlling signal 7a inputted from the outside, and numeral 3
designates a use or a fusible link received in a main fuse box. A
line for the output of the alternator and a power source line are
jointed at a point A which is located at the downstream side of the
fuse 3.
Numeral 4 designates a key switch, numeral 5 designates a current
sensor for detecting an output current I.sub.A from the alternator
2, numeral 5a designates a voltage signal corresponding to the
value of the output current I.sub.A, numeral 6 designates a current
sensor for detecting an electrical load current I.sub.L and numeral
6a designates a voltage signal corresponding to the electrical load
current I.sub.L. When the direction of current for charging the
battery 1 at the upstream side of the point A is assumed to be
positive, and the value of battery charging current is I.sub.B, a
relation of I.sub.A =I.sub.B +I.sub.L is established.
Numeral 7 designates a control unit (ECU) adapted to receive the
voltage signals 5a, 6a and a signal 9a and generates a control
signal 7a in accordance with a predetermined program by which the
output of the alternator 2 is controlled, and to generate a control
signal 7b by which an ISC valve (ISCV) 8 as an actuator for
controlling idling revolution is controlled. The signal 9a includes
a crank angle signal to obtain the number of revolutions of the
engine, a throttle opening signal for determining acceleration or
deceleration, an idle switch signal for detecting an idling
position of a throttle valve, an intake air quantity signal and a
signal from a starting switch, a gearing mechanism (by which a
neutral position or a gear-connection position is detected), a
brake switch or a headlight switch.
Numeral 10 designates an electrical load which is always applied to
the engine in operation. The electrical load includes various kinds
of control units including the ECU 7, an ignition coil, an injector
and so on. Numeral 11 designates a switch for another electrical
load 12, which is applied to the engine when the switch 11 is
turned on, the electrical load including a motor fan, a blower, a
rear defogger, headlights, power windows and so on.
The operation of the electronic control apparatus of the
above-mentioned embodiment will be described. Since the control
system of the electronic control apparatus is complicated,
description will be made by classifying the system into three
groups for easy understanding: (1) control of generation of
electricity in the alternator ((1-1) control of stopping generation
of electricity in the alternator at an acceleration time
(improvement of acceleration performance), ((1-2) control of
stopping generation of electricity in the alternator in a light
load condition (improvement of fuel cost), (1-3) control of the
load-responsive characteristic of the alternator (stabilizing
idling revolution)), (2) control of idling revolution ((2-1)
correction of ISC load (stabilizing idling revolution)).
As described above, the control of generation of electricity in the
alternator is classified into the control of stopping generation of
electricity at the time of acceleration which is mainly for
improving the acceleration performance, the control of stopping
generation of electricity in the application of a light load which
is mainly for improving fuel cost and the control of the
load-responsive characteristic which is for stabilizing the idling
operation. The operations of control are described in detail with
respect to time charts and flowcharts in the order of processing,
namely, processing of an acceleration time, processing of a light
load application time and processing of an idling time.
FIG. 2 is a flowchart showing a routine for controlling generation
of electricity at an acceleration time and FIG. 3 is a time chart
in the operation for the routine.
In FIG. 2, determination is made as to whether or not the engine is
starting at Step 401. When the engine is starting, the processing
of the routine ends The determination of the starting is made by
the operation of the starting switch. Since the operational
condition is unstable during starting of the engine, there is a
possibility of erroneously determining acceleration, and the
control of generation of electricity therefore should not be
performed.
At Step 402, the acceleration is determined. The acceleration is
generally determined by using a change of throttle opening degree
or a change of intake air quantity. In this embodiment, the
determination of acceleration is made when a change of throttle
opening degree assumes a predetermined value or higher as shown in
FIG. 3a, and then, an acceleration flag is set as "1" as shown in
FIG. 3b.
When the determination of acceleration is made, acceleration timers
1 and 2 are set at Step 403. These timers have such a relation of
acceleration timer 1<acceleration timer 2. Further, these timers
count down at respective rates until the values become 0, for each
predetermined time interruption treatment. The operation of the
acceleration timers 1, 2 is shown by operation waveforms in FIGS.
3c and 3d.
At Step 404, determination is made as to whether or not the
acceleration timer 2 counts 0. When affirmative, the processing
routine is finished. When a value counted is not 0, determination
is made as to whether or not the gear is in a connection state or a
disconnection state at Step 405. When the gear is in a connection
state, then, determination is made as to whether the headlights are
turned on or off at Step 406.
When the gear is in a connection state and the headlights are
turned off, the control of generation of electricity at an
acceleration time or the control of stopping generation of
electricity is conducted. Since the control of stopping generation
of electricity at an acceleration time is to improve an
acceleration performance, it is effective only when the gear is in
a connection state and the automobile is driven. When the control
of stopping generation of electricity at an acceleration time is
conducted when the automobile is driven while the headlights are
operated, the headlights become instantaneously dark (the voltage
is dropped from 14.5 V to 12.5 V). Accordingly, the control of
stopping generation of electricity is not conducted in order to
assure safety during the headlights being operated.
At Step 407, determination is made as to whether or not the
acceleration timer 1 is 0. When the acceleration timer 1 does not
show 0, the operation step is moved to Step 408 to stop generation
of electricity. Namely, the duty of the control signal 7a to be
supplied to the alternator 2 is made 0%. When the acceleration
timer 1 shows 0, the operation step is moved to Step 409 where the
control duty is increased by a predetermined value. In this case,
when the control duty is 100% or higher, it remains at 100%.
FIG. 3e shows a change of the control duty; FIG. 3f shows an output
current I.sub.A from the alternator 2 according to the change of
the control duty; and FIG. 3g shows a voltage in the battery 1. In
FIG. 3f, the output current I.sub.A of the alternator 2 increases
beyond 100% after the control of generation of electricity has been
performed. This is because lost power due to an electric discharge
by the battery 1 during the control of generation of electricity is
recovered.
FIGS. 4 and 5 are respectively a flowchart and a time chart
concerning the control of stopping generation of electricity at the
time of the application of a light load.
In FIG. 4, determination is made as to whether or not the
acceleration timer 2 is 0 at Step 601. When the acceleration timer
2 shows 0, the operation step is moved to Step 602. The operation
of Step 602 means that the operation of the acceleration timer 2
dominates over that of the acceleration timer 1.
At Step 602, determination is made as to whether the gear is in a
connection state or a disconnection state. When it is found that
the gear is in a connection state, the operation step is moved to
Step 603. It is because the number of engine revolutions during
idling is increased even though the generation of electricity is
stopped to reduce a load to the engine when the gear is in a
disconnection state.
At Step 603, determination is made as to whether the air
conditioner is turned on or off. When the air conditioner is in an
off state, the operation step is moved to Step 604. This operation
step is to prevent the battery 1 from exhausting by a consumption
power of air conditioner.
At Step 604, determination is made as to whether the headlights are
turned on or off. When headlights are turned off, the operation
step is moved to Step 605. This is because the headlights suddenly
become dark during the cruising of the automobile if the generation
of electricity is stopped during the turn-on time of the
headlights.
At Step 605, determination is made as to whether the brake is
turned on or off. When the brake is turned off, the operation step
is moved to Step 606. This is because the engine torque is
increased when the generation of electricity is stopped during a
braking-off time.
At Step 606, determination is made as to whether a light load flag
is set or reset. When the flag is in a reset state, the operation
step is moved to Step 607 where a threshold value I.sub.AT of the
output current I.sub.A of the alternator 2 is obtained with
reference to a previously prepared two-dimensional map which is
prepared by using factors of engine revolution and load. In this
case, charging efficiency (CE) is used as the load, and the
charging efficiency is previously obtained by dividing an intake
air quantity by a revolution number which is necessary to obtain a
fuel quantity in a routine (not shown). Instead of using the
charging efficiency, a boost value or a throttle opening degree may
be used.
At Step 608, an actual output current I.sub.A from the alternator 2
is read, and the actual output current I.sub.A is compared with the
threshold value I.sub.AT at Step 609. When I.sub.A
.ltoreq.I.sub.AT, the operation step is moved to Step 610 where the
light load flag is set in the determination that a light load is
applied. When not I.sub.A .ltoreq.I.sub.AT, the light flag is reset
at Step 615. At Step 611, the generation of electricity is stopped,
namely, the control duty is made 0%.
On the other hand, when the light load flag is determined at Step
606 to be set, a threshold value I.sub.LT of a load current I.sub.L
is obtained by calculation at Step 612. The calculation is
conducted with reference to a two-dimensional map which is prepared
by using factors of engine revolution number and load. An actual
load current I.sub.L is read at Step 613, and the actual load
current I.sub.L is compared with the threshold load current
I.sub.LT at Step 614. When I.sub.L .gtoreq.I.sub.LT, the light load
flag is reset at Step 615. Then, the control of stopping generation
of electricity is terminated and the ordinary control of generating
electricity is conducted at Step 616, namely, the control duty is
made 100%. When I.sub.L <I.sub.LT at Step 614, the control of
stopping generation of electricity is continued at Step 611.
In the time chart of FIG. 5, FIG. 5a shows a change of an
electrical load being turned on and off, FIG. 5b shows the output
current I.sub.A of the alternator and the threshold value I.sub.AT
when the control of stopping generation of electricity is started,
FIG. 5c shows a change of the light load flag, FIG. 5d shows the
load current I.sub.L and the threshold value I.sub.LT when the
control is finished, and FIG. 5e shows a change of the control
duty. In the FIG. 5, the load current is reduced after the
generation of electricity is stopped, however, the load current
does not become 0 because a constant electrical load such as the
electrical load 10 shown in FIG. 1 is always applied.
FIGS. 6 and 7 are respectively a flowchart and a time chart showing
the operation of the control of generation of electricity in
response to a load. At Step 801, determination is made as to
whether or not the acceleration timer 2 is 0. When the acceleration
timer 2 is 0, determination of idling is conducted at Step 802
through Step 805. Namely, at Step 802, determination is made as to
whether the gear is in a connection state or a disconnection state.
When the gear is in a disconnection state, determination is made as
to whether an idle switch is turned on or off at Step 803. When the
idle switch is turned on, an ISC target revolution number NE.sub.T
is read at Step 804. Then, determination is made as to whether or
not an engine revolution number NE is in a relation: NE
.ltoreq.NE.sub.T +K (K is a constant) at Step 805. When the
above-mentioned formula is established, the operation step is moved
to step 806 in the determination of an idling state. Otherwise, the
operation step is moved to 815 and the ordinary electricity
generation control is conducted.
Step 806 through Step 809 concern a routine as to whether the load
is increased or not. Namely, a load current I.sub.L (i) is read at
Step 806; the load current I.sub.L (i-1) at the previous time is
read at Step 807; a load current threshold I.sub..sub.LIT
=f{I.sub.L (i-1)} is calculated at Step 808; and determination is
made as to whether or not a relationship I.sub.L (i)-I.sub.L
(i-1).gtoreq.I.sub.LIT is established at Step 809. When the
relationship is established, the increase of the load current is
determined. Then, load-responsive timers 1, 2 are set at Step 810.
When the formula is not established, the operation step is moved to
Step 811.
The load-responsive timers 1, 2 are simultaneously set as shown in
FIGS. 7c and 7d wherein there is a relation of timer 1<timer
2.
At Step 811, determination is made as to whether or not the timer 1
is 0. When the timer 1 is not 0, the control of stopping generation
of electricity is conducted at Step 812. On the other hand, when
the timer 1 is 0, the timer 2 is examined at Step 813. When the
timer 2 is not 0, the control of generation of electricity (the
duty is gradually increased) is performed at Step 814. When the
timer 2 is 0, the ordinal electricity generating control is
conducted at Step 815.
More detailed explanation of the timers 1 and 2 will be made. The
control of the alternator in response to a load is to prevent the
number of revolutions of the engine from decreasing, when an
electric load is applied during the idling of the engine, the
control being used together with an ISC load correction control
(which will be described hereinbelow). Although it is known to
provide a switch for an electrical load and to increase an intake
air quantity at the time of operating the switch, it is not
economical to provide such a switch for each of electrical loads
because the number of connectors of the ECU7 is increased. In order
to eliminate such disadvantage, there has been known to use such a
technique that the alternator 2 itself detects a drop in battery
voltage when any of the electrical loads is connected and the
generation of electricity in the alternator is instantaneously
stopped, and then, the generation of electricity is gradually
increased. Such type of alternator is called a load-responsive type
alternator wherein the voltage is so controlled as to be gradually
returned to the original voltage in 5 through 10 seconds because it
is necessary to match a rate sufficient to comply with a revolution
number feedback control in the idle revolution control.
However, the above-mentioned technique has a disadvantage that
there is a change of load during the controlling operation, or the
headlights become dark for a relatively long time since a time of
controlling is long. As another technique of control, there is
known a method of load correction wherein an increase in electrical
load is detected from an amount of increase in the output current
of the alternator, and an intake air quantity is increased by means
of the ISC valve 8. However, there is a delay in engine stroke
(suction/compression/explosion/exhaustion) even though the air
quantity is increased, and there is a three-stroke delay until an
actual torque is produced. Accordingly, a drop in the number of
engine revolutions is unavoidable just after an electrical load is
corrected.
In accordance with the above-mentioned embodiment of the present
invention, a load-responsive control for the alternator and an idle
revolution load correction control are combined, whereby an initial
drop of voltage is prevented, and an excellent control of idling
revolution is obtained. The load responsive timer 1 is to
compensate a delay of stroke as described above and corresponds to
a time of about three strokes of engine. For instance, when an idle
revolution number is 750 rpm, it provides about 120 ms in a case of
using a four-cylinder engine.
The timer 2 is selected in a manner as follows. Namely, when an air
quantity is increased stepwisely by means of the ISC valve 8, an
air quantity sucked by the engine assumes an approximate value with
a first-order lag which are substantially determined by an air
volume VS at the downstream side of a throttle valve (which
corresponds mainly to a volume of surge tank) and a cylinder
capacity V.sub.C of each cylinder.
where T is a frequency of idle revolution. Accordingly, the time
period of the timer 2 is a time substantially equal to the time
constant .tau.+the time period of the timer 1. By suitably
selecting the above-mentioned factors, it is possible to obtain a
load-responsive control having a time of about 1 second or less,
and an excellent idle revolution control can be obtained in a
relatively short time.
FIG. 8 is a time chart showing the operation of the electrical load
correction control-in the idle revolution control wherein the idle
speed control valve (ISCV) 8 is controlled and an intake air
quantity to the engine is controlled. An increase in electrical
load is detected by detecting an increase in a load current I.sub.L
thus, control is conducted as mentioned below in response to an
increase of a predetermined load current. At the same time, the
alternator load-responsive control is conducted.
The duty ratio of the ISC valve 8 is increased in response to an
increase of a load current. The ISC valve 8 may be a linear
solenoid type to perform a duty control to control an air quantity.
On the other hand, an engine torque appears with about a
three-stroke delay (waste time) and a first-order delay. In this
case, the engine revolution assumes a line indicated by a character
C in FIG. 8e, if neither the alternator control nor the load
correction by the ISC valve 8 is conducted. The engine revolution
assumes a line indicated by a character B if the load correction by
the ISC valve 8 is not conducted. When the both of the alternator
control and the load correction by the ISC valve 8 are conducted in
accordance with the above-mentioned embodiment wherein the waste
time and the first-order delay are taken into consideration to
perform the optimum control, a stable idle revolution control can
be effected as shown by a line A without causing a drop in the
number of engine revolutions.
EXAMPLE 2
FIG. 9 shows the construction of a second embodiment of the present
invention. The second embodiment has a simpler structure than
Example 1 to reduce cost. Specifically, current sensors 5 and 6 are
gathered to a portion to thereby constitute a current sensor 50
having a simple structure. 51 and 52 designate current detecting
members for the current sensors 5 and 6 and numeral 53 designates a
circuit portion including an amplifier. The current sensor 50 can
be arranged near the main fuse box, whereby the current detecting
members 51, 52 can be closely located as if they form a one-piece
body.
The current sensor 50 is described with reference to FIG. 10. A
hall type current sensor is used for the current sensor 50. Numeral
51a designates a metallic bar through which a current flows,
numeral 51b designates a core, and numeral 51c designates a hole
element. When a current is passed through the metallic bar 51a,
magnetic fluxes corresponding to the current are generated in the
gap of the core 51b placed surrounding the bar 51a. The fluxes are
detected by the hole element 51c to convert them into an electric
signal. Numerals 51a through 52c designate the same elements as the
above-mentioned. These are called current detecting members. The
circuit portion 53 comprises a signal selector 53a and an amplifier
53b. The ECU7 selects the outputs of the current detecting members
51, 52 and receives an output as a voltage signal.
EXAMPLE 3
In Example 1, a load current I.sub.L is detected. However, a
battery charging current I.sub.B may be detected for the load
current I.sub.L. The current I.sub.A of the alternator is formed of
I.sub.L +I.sub.B, obtained by calculation when I.sub.A and I.sub.B
are detected. In this case, the construction of the third
embodiment is more complicated than that of the first embodiment
having the current sensors 5, 6 because it is necessary to detect
the direction of the current I.sub.B.
Thus, in accordance with the present invention, since generation of
electricity is stopped when an output current from the alternator
has a predetermined value or lower, and the generation of
electricity is resumed when a load current has a predetermined
value or higher, fuel cost can be improved and an excellent control
characteristic can be obtained. Further, since a load-responsive
control for the alternator and an increase in an intake air
quantity are conducted when the load current is increased, a drop
in the number of revolutions during idling can be prevented, and
stable idle revolution control can be conducted. In addition, the
generation of electricity by the alternator at an acceleration of
the engine is stopped for a predetermined time, and then, the
output of the alternator is gradually increased. Accordingly, the
acceleration characteristic can be improved by reducing a load to
the engine at the acceleration time.
Obviously, numerous modifications and variations of the present
invention are possible in light of the above teachings. It is
therefore to be understood that within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described herein.
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